In the delivery of physiologic amounts of testosterone to produce circulating concentrations approximating the normal circadian rhythm of healthy men, a system shown schematically in FIG. 1 is used. Proceeding from the top of the Figure toward the surface in contact with the patient's skin, the system is composed of 11 a transparent ethylene-vinyl acetate copolymer/polyester laminate as a backing film; 12 a drug reservoir of testosterone, alcohol, glycerin, glycerol monoaleate and methyl laurate gelled with an inert acrylic acid copolymer, 13 a permeable polyethylene microporous membrane; and 14 a peripheral layer of an adhesive surrounding the central, active drug delivery area of the system.
Prior to opening the system and applying the system to the skin, the central delivery system 12 is sealed with a peelable disc 15. The disc is composed of a five-layer laminate including a layer of aluminum foil which give the disc a silver appearance. The "silver" disc 15 is attached to, and removable with the release liner 16, a silicone-coated polyester film.
To use, the tabs 17a and 17b, extending from the patch 14 and the release liner 16, respectively, are gently pulled apart as shown in FIG. 2, to remove the liner 16 and the silver disc 15. This operation will expose the adhesive layer 14 and the central reservoir area 12 covered by the microporous membrane 13. The resulting patch is then applied to the skin by pressing the adhesive layer 14 firmly against the skin.
Such systems have been used successfully for many years for topical administration of many medicinal and therapeutic materials. However, in recent years the use of such systems, particularly with heart patients who must consume relatively high dosages of blood-thinning medication, has produced bleeding problems. The simple explanation lies in the adhesive layers used in the delivery systems. When the patches that are firmly adhered to the patient's skin are removed, the thin skin of the heart patient tends to be removed as well, resulting in immediate bleeding.
The object of the present invention is to overcome this dangerous problem.
Specifically, the object of the present invention is to provide a drug delivery system for the topical administration of therapeutic or medicinal material without contacting the patient's skin with an adhesive and without losing any of the efficiency of the drug delivery system.
Other objects will appear hereinafter.